The two vessels worked together in the patch for 12 days but operated independently most of the time. New security guidelines prohibit scientists from boarding or even sharing samples or equipment with a vessel from another country.

The American team went to work lowering equipment over the side to collect water samples. They analyzed water chemistry, nutrients, and microorganism diversity. Working to assist their Japanese colleagues on board both vessels, they made these measurements to characterize how the phytoplankton responded to the iron enrichment over a 32-day period. They also ran experiments on deck to learn how available the iron was in the patch, how diatoms were growing and coming together in multi-cellular aggregations. They studied the sinking rate, the slow process through which aggregations of diatoms sink into the deep sea, taking their carbon with them.

The Kilo Moana returned to Hawaii after spending 42 days at sea. Early results suggest that the struggle for iron may indeed follow something like what happens in the soil. Wells and his colleagues are evaluating the data they collected and conducting additional laboratory experiments.

UMaine scientists are planning to return to the Pacific in 2007, but they have a different destination in mind. Work by Japanese and Canadian researchers has already shown that the consequences of iron additions may vary from the eastern to the western North Pacific. Even with additional iron, large phytoplankton cells in the east do not appear to grow as readily. Since prevailing winds tend to blow iron rich dust off the Asian continent into the Pacific, it may be that phytoplankton closer to the source of that dust may be primed to respond differently.

Wells and his colleagues will be studying the possibili
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Contact: Mark Wells
mlwells@maine.edu
207-581 -4322
University of Maine
25-Feb-2005